Osteosarcoma is the most common type of bone tumor, but the lack of good biomarkers to predict the outcome of standard treatment has so far prevented patient stratification and therapy evolution. Gene expression signatures, including microRNA (miRNA) profiles, have been suggested to have predictive value for the response of a tumor to chemotherapy, but the limited availability of frozen tissue samples has hindered development of signatures with prognostic value for recurrence and survival. Formalin-fixed paraffin-embedded tissue (FFPE) is the standard sample used by histopathological laboratories but it has proved very challenging to use this for reliable expression-profiling.

This problem has now been overcome by Dimitrios Spentzos and colleagues, whose study was recently published in Genome Medicine. The researchers used FFPE samples to analyze the association of miRNA expression profiles with disease prognosis. They identified, in the largest cohort to date, miRNA signatures with predictive value for osteosarcoma recurrence and survival. The miRNAs clustered mainly on the 14q32 locus, already known to be implicated in this type of cancer. In addition, they also found distinct miRNA signatures with predictive value for chemoresponse, confirming the involvement of some previously reported miRNAs in this phenomenon.

This study provides the first set of miRNA prognostic signatures for treatment outcome in osteosarcoma using FFPE samples, which should allow for improved recurrence risk assessment and the design of more specialized therapies. Perhaps more importantly, it lays the ground for the use of FFPE samples in cancer miRNA profiling, which should contribute to the advance of biomarker discovery in rare cancer types.

This study is part of the recently launched Pharmacogenomics series, which will feature two more articles this month: a research article from Matthias Schwab and colleagues on the influence of genetics of human hepatic uptake transporters on their expression, with implications for atorvastatin treatment, and a review by Ann Daly, which provides an overview of the field of pharmacogenomics of adverse drug reactions.